The present invention relates to a heat dissipation system for use in a suspension system. More particularly, the present invention relates to a heat sink and heat dissipation arrangement that cools the damping fluid of a suspension system, thereby improving the performance, as well as the life, of the damping components.
In the past, suspension systems in general have been used for many applications, including cushioning impacts, vibrations or other disturbances experienced by vehicles and machinery. Typical applications, for example, include the use of suspension systems in bicycles and motorcycles.
For example, bicycles have been developed with suspension systems for cushioning impacts or vibrations experienced by the rider when the bicycle contacts bumps, ruts, rocks, pot holes or other obstacles and road variations. Typically, such bicycle suspension systems have been configured for use in the front or rear bicycle fork, in the head tube that connects the front fork to the bicycle frame and handlebars, in the seat post, and in conjunction with a rear wheel swing-arm assembly, among other locations.
Typically, a suspension system is provided in the form of two slidable tubular elements with a spring element or system provided therein. The spring system biases the tubular elements into a spaced apart condition when the suspension system is under neutral (i.e., no external load) conditions. The tubular elements are positioned to slidably move with respect to each other upon impact to the frame, with the spring system therein resisting the compression forces. Depending on the type of spring used, the spring system stores some, if not all, of the energy imparted to the system during compression and releases the energy to return the tubular elements to their neutral position.
Bicycles incorporating suspension systems have become increasingly common. One popular form of a bicycle suspension system is a suspension fork having at least one, and usually a pair, of upper tubular fork elements slidable with respect to a pair of lower tubular fork elements, both pairs straddling the front wheel of the bicycle. Because the upper fork elements are preferably telescopically slidable with respect to the lower fork elements, the upper or lower elements may be considered inner fork elements, and the other two elements may be considered outer fork elements within which the inner fork elements slide. Typically, the upper pair of tubular elements are the inner fork elements and the lower pair are the outer fork elements. However, the reverse arrangement may also be used.
In order to enhance the performance of suspension systems further, damping systems have been provided to dampen the motion of the suspension system. Such damping systems may be formed within the tubular elements of the suspension system as in U.S. Pat. No. 5,445,401 to Bradbury and U.S. Pat. No. 4,561,669 to Simons which patents are expressly incorporated herein by reference in their entirety. More preferably, the damping system may be provided in a self-contained damping cartridge, as described in U.S. Pat. No. 5,456,480 to Turner et al., which is expressly incorporated herein by reference in its entirety. Such damping cartridges provide a number of benefits. For example, damping cartridges typically reduce overall weight (because less damping fluid or gas is needed), permit simplified interchangeability and replacement of the damping components, and generally reduce the amount of leakage that may occur from the damping system.
The amount of energy absorbed by the suspension system and its damping system depends on the path or terrain over which the bicycle or motorcycle is ridden, as well as the bicycle/motorcycle speed, rider weight, frame type, wheel thickness and other factors. Frequently, a great amount of heat may be generated by the damping system, adversely affecting the damping characteristics of the system and increasing the internal pressure of the cartridge as the damping fluid expands, thus detrimentally affecting the structure of the seals and other components of the damping system as well. In particular, damping cartridge failures are often associated with severe riding conditions, such as those that occur during downhill racing. Therefore, dissipation of the heat generated by a damping system is important for the proper functioning of the damping system, and reduces the likelihood of cartridge failures.